Consumers have long demanded higher fuel efficiency. One line of technological development to meet this demand has involved changing the structure of the vehicle. Size, shape and offered features impact the miles per gallon. Perhaps the most efficient of vehicles using this line of technology is the motorcycle, which most commonly get about fifty miles to the gallon.
Another line of technology focuses on the fuel itself. People have known that liquid fuel does not burn. Vapors around the liquid will burn. In fact, chemists will state that if one could put a lit match into liquid fuel in the absence of vapors, the match will extinguish. In typical vehicles, some believe that only about 18% of the fuel is in vapor form prior to and during ignition in the internal combustion engines. The balance of the fuel is sent out of the vehicle through the exhaust system. The catalytic converter conditions the unconsumed fuel prior to release into the atmosphere. Technology, focusing on conditioning of the fuel, vaporizes a greater percentage of the fuel, thereby gaining an improve energy recovery.
Generally, the vaporizing devices use excess energy from the engine. Heat energy can be drawn off the exhaust or cooling system. Some use the excess electrical energy as an energy supply. This energy is transmitted to the fuel usually in one of a few manners. The most popular appear to be mist vaporizers and boilers.
Mist vaporizing systems in general terms atomize the fuel into a mist form and apply heat to convert the mist into a vapor. These systems take advantage of the fact that mist, has far greater surface area, making it more readily converted to vapor, than a pool of fuel. Unfortunately these mist vaporizing systems are generally not operational until after the vehicle has warmed, since the atomized fuel tends to pool before heat is abundant and pooling fouls the system. Wasteful adaptation to address the pooling are found in most of these systems.
As an example, Covey Jr. (U.S. Pat. No. 5,291,900) discloses a Fuel Vaporizing System. The system has an inner and outer housing with a temperature probe therebetween. Exhaust passes between the inner and outer housings. Atomized fuel is injected into the inner housing. The fuel, mist form, is converted to vapor as it rises through a series of baffles. This system, by its own admission, is not operational until the probe detects a temperature of at least 550 degree F. The waste here is in not being able to use the system until the vehicle has warmed well and the waste is experienced in cold climates and on short trips.
Covey Jr. (U.S. Pat. No. 4,368,163) discloses an Apparatus for Vaporizing Fuel for Engine in Conjunction with Carburetor. Atomized fuel is sprayed at a conduit containing exhaust. The conduit, a heat exchanger, causes the mist to vaporize. Any mist that fails to vaporize pools in a well and is drained back into the fuel line. This invention is wasteful in requiring additional apparatus to merge two streams of fuel and having lower vapor production in cold climates and on short trips.
A boiler system may be used to evaporate fuel from a pool of liquid fuel. This has the advantage of being usable before the exhaust or cooling systems are fully heated. However, boilers are inefficient and have lower vapor production in that they do not take advantage of the well accepted atomizer technology, which greatly increases the surface area of the fuel and eases the conversion liquid fuel to vapor.
For example, Lahti et al. (U.S. Pat. No. 6,415,775) discloses a Preheat Fuel Delivery System. This system directs air through a bubbler tank. Vapors are collected above the pool of fuel. Advantageously, this system will work when fuel pools. Unfortunately, the surface area from which the fuel may vaporize is greatly reduced from the surface area that would be present should the fuel be heated from a mist form. This system compensates for low vapor production, routing exhaust into the bubbler, which unfortunately mixes carbon dioxide (not oxygen) with the vaporized fuel.
Cook (U.S. Pat. No. 5,746,188) discloses another example of a boiler system entitled Apparatus for Supplying Fuel to an Internal Combustion Engine. Liquid fuel is injected into the interior of the housing. The liquid fuel passes through openings in the baffles gathering heat and eventually vaporizing prior to exiting the housing. Advantageously, this system will work when fuel pools. Unfortunately, the surface area from which the fuel may vaporize is greatly reduced from the surface area that would be present should the fuel be heated from a mist form, yielding lower vapor production.
What is needed is a fuel vaporization system that vaporizes fuel while in a mist form and yet will also vaporize, e.g., boil, fuel while in a pooled form. The system should avoid the waste attendant with evacuating or avoiding pooled fuel and likewise should capture the higher vapor production attainable when vaporizing fuel in a mist form. Desirably, the components are minimal and are used both for vaporizing the mist and boiling the fuel pools.